The present invention relates to golf clubs, golf shafts, and inserts for golf club shafts, and, in particular, to an improved golf club shaft having a coil or coil-type insert for enhanced swing weight control, stiffness and flex control, shock absorption, vibration elimination or reduction, and other club improvements.
Conventional golf club shafts are made of steel, metal alloys, or composite materials. Shafts have a tapered shape starting from the smaller tip end to the larger butt end and are normally formed with a continuous variable dimensional difference along the entire length of the shaft.
When a golfer hits a shot, the shaft is subjected to a number of complex forces during the swing, at impact, and during the follow through. Generally, conventional shafts have limited control over the swing weight of the club or the control of the torsion applied to the shaft during the swing. Similarly, conventional shafts do not control or adequately eliminate shock and vibration that transfer through the shaft to the golfer's hands, particularly at impact. Furthermore, conventional shafts have limited means to properly control the stiffness and the flexing of the shaft during the swing and therefore do not provide optimum shot control, power transfer, and accuracy.
It is known that the stiffness and/or flexibility of the shaft as well as the flex points thereon can be varied to at least some degree to better fit the shaft to the physical parameters and swing characteristics of a particular golfer. However, the physical characteristics of conventional shafts and the costs associated with producing a properly “fitted” shaft obviously limits the degree to which a particular golfer can obtain or afford the best possible shaft for his or her swing.
There are a number of prior art patents dealing with shaft flexibility and variations in flex point. Some prior art patents of interest relating to golf shafts are shown in Design Pat. No. 236,735 to Bush, U.S. Pat. No. 5,022,652 to Fenton, British Patent No. 471,020, to TRI-ON, and U.S. Pat. No. 5,316,299 to Feshe et al. In the inventor's opinion, these patents and the described inventions have not satisfied the need for a shaft or the combination of a shaft and club head which provides the most optimum characteristics, at an affordable price range for the majority of golfers worldwide.